Here’s the Scoop on the 2018 North Carolina Energy Conservation Code

Originally Published September 25, 2018

New construction home almost complete

North Carolina Energy Conservation Code (NCECC) Updates

Hopefully by now you’re all aware that NC adopted a new building code on January 1st, 2019. As your energy experts, we’ve highlighted the top 5 most notable changes you’ll want to pay attention to in the 2018 NCECC:

Topic 01

Soffit Baffles

A long standing best practice is now explicitly called out as a requirement:

R4R402.2.3 Soffit Baffles

“For air-permeable insulation in vented attics, a baffle shall be installed adjacent to soffit vents. The baffle shall extend over the top of the attic insulation. The baffle shall be permitted to be any solid material.”

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Topic 02

Climate Zone Specific Insulation & Fenestration Changes

There are minimal changes to all zones but most notable climate zone 3 will be required to have R-38 ceiling insulation and R-15 or R-13+2.5 wall insulation.

TABLE R402.1.2 Insulation and Fenestration Requirements by Component

Climate Zone Fenestration U-Factor Skylight U-Factor Glazed Fenestration SHGC Ceiling R-Value Wood Frame Wall R-Value Mass Wall R-Value Floor R-Value Basement Wall R-Value Slab R-Value & Depth Crawl Space Wall R-Value
3 0.35 0.55 0.30 38 or 30ci 15 or 13+2.5 5/13 or 5/10ci 19 5/13 0 5/13
4 0.35 0.55 0.30 38 or 30ci 15 or 13+2.5 5/13 or 5/10ci 19 10/15 10 10/15
5 0.35 0.55 NR 38 or 30ci 19 or 13+5 or 15+3 13/17 or 13/12.5ci 30 10/15 10 10/19

Topic 03

Building Thermal Envelope

Seams and joints of exterior house wrap and knee wall backing will be required to be sealed per the manufacturer’s instructions.

R402.4.1 #5

“Exterior house wrap material joints and seams are required to be sealed per the manufacturer’s instructions or, if house wrap joints are not sealed, seal exterior sheathing and exposed band joist joints including perimeter joints and edges of these materials.


  • Spray Foam in building thermal envelope wall systems
  • Wall sheathing joints where wall sheathing is fully glued to framing”

R402.2.15 Attic Knee Walls

“… Joints shall be air sealed”

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Topic 04

Duct Leakage

Duct leakage testing is still a mandatory item under the 2018 NCECC and the benchmark targets have moved to 5% total or 4% leakage to outside. The previous target had been set at 6% total.

R403.3.3.1 & R403.3.3.2

“Duct testing and duct leakage shall be verified by compliance with either section R403.3.3.1 (Total duct leakage shall be less than or equal to 5 cfm per 100 square feet) or R403.3.3.2 (Leakage to the outside shall be less than or equal to 4cfm per 100 square feet).”

403.3.3 Exemption #3

“Duct systems serving areas of 750 square feet or less shall not need to be required to be leak tested”

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Topic 05

Energy Rating Index Compliance Alternative

The 2018 NCECC will now allow an Energy Rating Index (ERI) as a compliance pathway.

Check out our quick guide to Energy Code Compliance Pathways here → 

What's next?

Need support with these updates?

This is only an abbreviated list of the most impactful changes. You can download a copy of the entire NCECC via the IECC website (Be sure to select 2018 under the “current adaptations” tab in the top left corner). Schedule a call or fill out a form below to let us know if you still have questions, we’re happy to help!

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